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--  This file is a part of Technica Corporation Wizardry Project

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--  Copyright (C) 2004-2009, Technica Corporation  

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-- Module Name: read_data_buffer - Behavioral 

-- Project Name: Wizardry

-- Target Devices: Virtex 4 ML401

-- Description: Behavioral description for read data buffer.

-- Revision: 1.0

-- Additional Comments: 

--

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library IEEE;

use IEEE.STD_LOGIC_1164.ALL;

use IEEE.STD_LOGIC_ARITH.ALL;

use IEEE.STD_LOGIC_UNSIGNED.ALL;

use work.MAC_Constants.all;

---- Uncomment the following library declaration if instantiating

---- any Xilinx primitives in this code.

--library UNISIM;

--use UNISIM.VComponents.all;

entity read_data_buffer is

    Port ( clock : in  STD_LOGIC;

           reset : in  STD_LOGIC;

                          clear_buffer : in STD_LOGIC;

           push : in  STD_LOGIC;

           pop : in  STD_LOGIC;

           data_in : in  STD_LOGIC_VECTOR(data_width -1 downto 0);

           data_out : out  STD_LOGIC_VECTOR(data_width -1 downto 0);

                          buffer_full : out std_logic;

                          buffer_empty : out std_logic

                          );

end read_data_buffer;

architecture Behavioral of read_data_buffer is

signal data_array_v : burst_read_data_array;

signal var_a, var_b : integer range 0 to burst_length -1;

signal count_v : std_logic_vector(2 downto 0);

signal empty_s, full_s : std_logic;

signal count_v_s : std_logic_vector(2 downto 0);

begin

read_burst_data : process(clock,reset,pop,push,count_v,data_array_v,clear_buffer)

begin

if clock='1' and clock'event then

      if (reset='1' OR clear_buffer = '1') then

                        var_a <= 0;

                        var_b <= 0;

                        count_v <= "000";

                        for i in 0 to (burst_length -1) loop

                                data_array_v(i) <= (others => '0');

                        end loop;

                else

                        if(push = '1') then -- AND full_s = '0') then

                                if(count_v < "100") then

                                        Data_array_v(var_a) <= data_in;

                                        count_v <= count_v +1;

                                        if(var_a = burst_length -1) then

                                                var_a <= 0;

                                        else

                                                var_a <= var_a +1;

                                        end if;

                                end if;

                        elsif(pop = '1') then -- AND empty_s = '0') then

                                if(empty_s = '0') then

                                        count_v <= count_v -1;

                                        if(var_b = burst_length -1) then

                                                var_b <= 0;

                                        else

                                                var_b <= var_b +1;

                                        end if;

                                end if;

                        else

                                count_v <= count_v;

                                var_a <= var_a;

                                var_b <= var_b;

                        end if;

                end if;

end if;

count_v_s <= count_v;

data_out <= Data_array_v(var_b);

end process read_burst_data;

--FULL_s      <=  '1' when (conv_integer(count_v_s) = stack_depth)  else '0';

FULL_s      <=  '1' when (conv_integer(count_v_s) = 1)  else '0';

EMPTY_s     <=  '1' when (conv_integer(count_v_s) = 0) else '0';

buffer_full <= full_s;

buffer_empty <= empty_s;

end Behavioral;